1. Field of the Invention
Generally speaking, the present invention relates to the field of laser etching. More specifically, an embodiment of the present invention is a compact laser etching device, system, and method with a fixed optical path for etching indicia, such as a Vehicle Identification Numbers (VIN), onto a substrate such as a piece of glass, such as a vehicle window, metal, or other inorganic oxide.
2. Description of Prior Art
FIG. 1 shows a prior-art laser etching system 10. The prior-art system 10 included a large gantry structure 12. A laser 14 was mounted on a motion platform (i.e. trolley) 16 for movement back and forth on the gantry structure 12. An optical arm 18 comprising straight segments connected by mirrored optical joints provided a flexible light path from the laser 14 to a delivery head 20. In use, the delivery head 20 was placed against a glass window 22 of a vehicle 24. An operator stood behind the delivery head 20, held a handle 26 attached to the delivery head 20, and pulled a trigger 28 on the handle 26 to fire the laser 14 and etch the window 22. A laser beam steering system 30 was incorporated into the delivery head 20 to steer the laser beam to create the desired etching pattern. Electronics 32, 34 for driving the laser 14 and the steering system 30 were remotely located from the delivery head 20.
Disadvantages of the prior-art laser etching system 10 include the large mass of the laser 14 and associated systems, alignment and loss issues with the optical arm 18, and the electronics 32, 34 being remote-ed several times. A flexible, and changeable optical path, particularly with the optical arm 18 having many reflective surfaces, causes losses inherent in the design. Thus, to compensate for the losses, the laser 14 was required to be overpowered and heavy.
The laser 14 was typically 20 to 50 watts, and, as mentioned above, was suspended on top the gantry structure 12 and moved back and forth. All of the laser drive electronics were located on the motion platform 16 with the laser 14 and moved with the laser 14 under motorized control. The optical arm 18 was attached to the laser 14 to allow motion of the delivery head 20. The operator handled the delivery head 20 with the assistance of a tool balancer 36 and suspension cable 38, and held the delivery head 20 against a glass window 22 of a vehicle 24. The delivery head 20 had a fair amount of mass, and was mostly subject to damage in the optical alignment. The laser 14 was typically water-cooled.
Another prior-art system, known as a one-knuckle rotation system, is described and shown in U.S. patent application Ser. No. 10/625,783, which is incorporated herein by reference. The one-knuckle rotation system included an emitter housing including a laser, and a marking head joined to the emitter housing by a pivot joint and containing a beam directing apparatus and a lens. In this one-knuckle rotation system, an optical path from the laser to an emission port of the marking head is defined by an alignment mirror in the emitter housing, a through-running passage in a pivot joint, the beam directing apparatus, and the lens. The beam path changed based on the location of the laser relative to the head. The one-knuckle rotation system included integrated RF electronics for driving the laser (e.g., an exemplary integrated RF electronics and 30 watt laser for etching glass had a combined weight of about 16 pounds), contributing to a rather significant weight for the one-knuckle rotation system. Users complained of the one-knuckle rotation system as being too fatiguing, too hard to handle, and creating too much wear on the wrist.
Additionally, in both the prior art laser etching system 10 of FIG. 1, and the one-knuckle rotation system, the systems verified that laser was fixed to a window and ready to mark by the activation of micro switches positioned on the front of the marking head that depressed against the window, sending a signal that the device was ready to mark, or positioned to mark. These micro switches required additional space in the marking head and created additional mechanical failure points.